A wireless communication system is widely used to provide various types of communication services. For example, the wireless communication system provides voice and/or data services. The wireless communication system can use a frequency division duplex (FDD) scheme or a time division duplex (TDD) scheme. In the FDD scheme, uplink transmission and downlink transmission are achieved at the same time point while occupying different frequency bands. In the TDD scheme, uplink transmission and downlink transmission are achieved at different time points while occupying the same frequency band.
In order to effectively use limited radio resources in the wireless communication system, there are proposed methods and utilization for further effective transmission and reception in time, space, and frequency domains. Orthogonal frequency division multiplexing (OFDM) uses a plurality of orthogonal subcarriers. Further, the OFDM uses orthogonality between inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT). A transmitter transmits data by performing the IFFT. A receiver restores original data by performing the FFT on a received signal. The transmitter uses the IFFT to combine the plurality of subcarriers. The receiver uses the FFT to split the plurality of subcarriers. According to the OFDM, complexity of the receiver can be reduced in a frequency selective fading environment of a broadband channel, and spectral efficiency can be increased when selective scheduling is performed in a frequency domain by using a channel characteristic which is different from one subcarrier to another. Orthogonal frequency division multiple access (OFDMA) is an OFDM-based multiple access scheme. According to the OFDMA, efficiency of radio resources can be increased by allocating different subcarriers to multiple users.
The institute of electrical and electronics engineers (IEEE) 802.16 standard group was established in 1999 for broadband wireless access (BWA) standardization. A Wireless MAN-OFDMA standard has recently been defined to use the OFDMA. At present, a logical frame structure of an IEEE 802.16-2004 system uses the TDD scheme in which a downlink frame and an uplink frame are separated by a guard time.
Accordingly, there is a need for a method capable of transmitting data by using a frame having a shorter length than a frame structure of the TDD scheme in consideration of improvement of cell coverage, maximization of spectral efficiency, improvement of efficiency for mobility support, improvement of latency, etc.